Get label string per device in LVS device extraction

[srooks10]

Hi Matthias,

I have a LVS deck where some device families are extracted as black boxes because their geometry is too complicated to extract directly. Therefore I tag each of them with several labels and write a rule for each expected label combination (computing derived layers etc). For that I need to know each label in advance. To simplify the flow and the logic, I would like to have one rule per family and extract the label strings per device. The labels would then be shared in the extracted netlist as a parameter, for example to verify against the schematic.
Is it a reasonable feature request for KLayout?

[klayoutmatthias]

Hi @srooks10,

black box device extraction is not entirely uncommon, but the devices from a certain class need to share some common features, like the number of pins or the parameters to be extracted. Also, parameters are strictly numerical currently.

For example, an inductor is a coil drawn in metal layers, and computing the inductance from the polygon geometry is too tedious. So you can use a label to indicate the inductance and use that to specify the value. But you cannot for example, place a label that indicates the metal layer used for the coil (important for the model). So if you have three metal layers, you need three different extractors. You can simplify the task by coding one parameterized extractor and instantiate the actual extractors by creating three extractor instances from the same class, and using some "coil layer" parameter to specialize for Metal1 coils, Metal2 coils etc.

Each of these inductions has an infinite number of variations as the continuous parameters are conveyed trough labels instead of geometry, but there is a limited number of different classes - i.e. one per metal configuration. In general, the complexity of that scheme seems to be manageable.

I wonder if your case is similar to that one or if I am missing something.

I thought about introducing string-type parameters in addition to the numeric (continuous) values, so you could extract parameters from labels which are some family or model name for example. Is that what you mean?

I think I need an example to better understand what you are doing and where you hit some limitation.

Best regards,

Matthias